Mucopolysaccharidosis type I (MPS I) is an autosomal recessive storage disease caused by the absence of - L-iduronidase (IDUA), resulting in systemic accumulation of glycosaminoglycan (GAG) storage materials, hepatosplenomegaly, skeletal dysplasias, cardiopulmonary obstruction, progressive neurologic impairment and death by age 15. MPS I is currently treated by enzyme replacement therapy and by allogeneic hematopoietic stem cell transplantation, but these treatments are extraordinarily expensive and do not fully address the skeletal, cardiac and neurologic manifestations of the disease. Here we propose an entirely novel approach to the treatment of MPS I. Immusoft Corp. is developing genetically engineered autologous human B cells for production of therapeutic proteins upon infusion into patients. Discovery Genomics, Inc. (DGI) focuses on clinical development of the Sleeping Beauty (SB) transposon system for integrative gene transfer and expression. Here we propose to combine Immusoft's novel B cell expression platform with DGI's advanced DNA-mediated cellular genetic engineering technology for the purpose of expressing human IDUA from B cells in vivo as an approach to achieve systemic expression of IDUA as a treatment for MPS I. This collaborative project is further strengthened by the extensive experience of DGI's investigative team and colleagues at the University of Minnesota in the conduct of preclinical studies and clinical trials of new treatments for lysosomal storage diseases, in particular MPS I. For this Phase I study, the Specific Aims are; (i) Sleeping Beauty mediated human iduronidase gene transfer and expression in primary human B cells cultured in vitro. B cells will be isolated from human blood and expanded in culture using Immusoft's Immune System Programming technology. Early in the expansion process, cells will be collected and nucleofected with SB transposon DNA encoding human IDUA along with a plasmid encoding SB transposase to mediate integration into host B cell chromosomes. (ii) These cells will then be infused into immunodeficient (NOD-SCID), IDUA deficient mice, evaluating recipient animals for engraftment, expression and distribution of IDUA activity, and correction of metabolic and neurologic disease. Results from these studies will be directly applicable to the development of a clinical protocol for treatment of human MPS I by infusion of B cells genetically engineered using the SB transposon system.